GB748878A - Improvements in or relating to the production of solid non-ionic surface active agents - Google Patents

Abstract

A liquid non-ionic surface-active agent comprising a compound having in the molecule a chain of condensed ethylene oxide groups is converted into solid form by mixing the liquid agent with an excess by weight of solid urea in the presence of a reaction diluent and, as a reaction activator, a compound having a solvent action on urea, maintaining the mixture until urea adduct formation has taken place, separating the solid product and utilizing the recovered liquid phase for the treatment of further quantities of liquid agent and urea, wherein the mixing takes place in a separate mixing zone and the maintenance of the mixture under reaction conditions takes place in a separate reaction zone, the mixing zone being operated batchwise, each batch of mixed reactants being passed as a slurry into the reaction zone wherein the solid components and part of the liquid phase of the batch form a layer upon the solid components and part of the liquid phase of a batch previously discharged thereto, slurry being withdrawn continuously or batchwise at the bottom of the reaction zone and being passed to a filtering and/or centrifuging zone for the separation of solid product from the liquid phase, the liquid phase being recycled, at least in part, as reaction activator and diluent to the mixing zone. The relative volumes of the mixing and reaction zones are arranged, in general, to provide a holdup period in the reaction zone sufficient for completion of the reaction, say 12 to 60 hours. The term "reaction diluent" denotes a liquid hydrocarbon which does not form a urea adduct or a mixture of hydrocarbons containing only a small proportion of hydrocarbon which forms urea adducts at the temperature of the reaction, e.g. n- and iso-pentanes and hexanes, cyclopentane, cyclohexane and 40-150 DEG C. petroleum ethers. Reaction activators include water, C1-3 alcohols, glycerol and ketones such as acetone and methyl ethyl ketone. The liquid surface-active agents and general conditions for adduct formation are as described in the parent Specification. A preferred class of liquid agent is that described in Specification 748,881. A process described with reference to a flow diagram (not shown) comprises treating the liquid agent with SO2 or an acid as described in Specifications 748,879 and 748,880 and then stirring the treated agent with solid urea and a mixture of reaction diluent and activator. The slurried mixture is passed to a reaction zone and further batches are likewise prepared and added to the partially loaded reaction zone. When the reaction zone is fully loaded, slurry is withdrawn from the base and separated diluent containing activator is allowed to overflow from the top at rates equal to that of the mixture fed to the zone. The withdrawn slurry is filtered to obtain the solid adduct and the filtrate is recycled to the mixing zone, a portion, however, first being withdrawn and distilled to separate slow adducting oil therefrom. According to the Provisional Specification, any liquid non-ionic surface-active agent may be used. Specification 748,877 also is referred to.